Verizon argued that the FCC is barred from considering alternative possibilities for how the spectrum could be used, for example, if the cable companies sold it to T-Mobile instead.
In a filing on Monday with the FCC, T-Mobile argued that Verizon already has the most spectrum of any wireless carrier and that the deal would allow it to block its competitors access to the valuable resource.
But Verizon rejected arguments that it is "warehousing" the spectrum it already owns, saying the accusation is "demonstrably false."
Verizon called itself a "good steward of spectrum," and said that it needs the spectrum to meet its customers' "skyrocketing" demand for 4G LTE service.
Consumer groups have warned the deal will tilt the wireless industry toward duopoly, with Verizon and AT&T dominating the market.
But Verizon argued that the wireless industry is "intensely competitive." The company noted that in many markets, Clearwire, a wireless Internet provider, owns more spectrum than either AT&T or Verizon.
Verizon also rejected arguments that regulators should impose conditions on the deal, such as capping roaming rates or imposing interoperability requirements.
"These claims are not related to the transactions under review, but rather are efforts by commenters (mostly competitors) to advance their own broader regulatory agendas," Verizon wrote, adding the issues should be dealt with in the context of an industry-wide proceeding.